Shadowless lighting apparatus



May 19, 1931.. v H. L. M. J. BENARD 1,806,384

'SHADOWLES S L .i GHT ING APPARATUS Filed April 19, 1928 5 .5 lnven/z'or1 E an/m l M11 0 fie'numd Patented May 19. 1931 UNITED STATES PATENT 01F105:

' HENRI LUGLIEN MARIE JOSEPH BEN'ARD, OF PARIS, FRANCE, ASSIGINOR TOANCIENS ETABLISSEMENTS BARBIER, BENARD & TURENNE, SOCIETE ANONYME, 0FPARIS, FRANCE, A JOINT-STOCK COMPANY OF FRANCE SHADOWLESS LIGHTINGAPPARATUS Application filed April 19, 1928, Serial No.

The present invention relates to certain improvements applicable tolighting apparatus which do not throw shadows, and are more particularlyintended to lighting up operating benches or the like.

These lighting apparatus broadly comprise, as is well known, one or morecentral luminous sources about which is located the re flectng systemwhich reflects the luminous m rays emanating from the luminous source onto a given portion of the operating bench at different angles, whilst anoptical system, constituted by optical lenses or by combination ofmirrors and reflectors indifferently,

is preferably inserted between the luminous source or sources and theabove mentioned reflecting system.

A first improvement with which the present invention is concerned isintended to render these lighting apparatus more secure and suchimprovement essentially consists in fitting up a shadowless lightingapparatus with an emergency lighting device constituted by one or moreluminous sources completely independent of the principal luminous sourceor sources. When these auxiliary lighting sources are electrical, theyare mounted in a shunt circuit ofthe circuit of the main sources inorder to render them independent. .More advantageously, the auxiliarysources may be mounted on a totally separate circuit fed for example bya battery of accumulators.

The emergency lighting sources will be preferably arranged in such wisethat the light they emit shall be reflected back at different anglesonto the surface to be lit up, said emergency lighting source thusitself providing to a certain extent shadowless illumination. The objectof this emergency source of illumination when it operates in conjunctionwith the principal lighting system, Wlll likewise be to project light onthe portions fringing the operating bench, which are nor- ;5 mally notlit up.

Another improvement forming the ob 'ect of the present invention aims atobviatin another drawback obtaining with devices 0 this nature as atpresent known and which resides in the fact that they give off greatheat Wl'llCll 271,277, and in France February 10, 1928.

may seriously inconvenience the surgeons. This heat is given off by theinfra-red rays emitted by the principal luminous source or sources. Thisimprovement consists in combining with a lighting apparatus that doesnot throw shadows, a device inserted in the path of the luminous raysbetween the luminous emitting source or sources and the surfaceto be litup, such device being capable of absorbing the heatcarried by said rays.

According to a form of construction, the heat absorbing device isconstituted by heat absorbing glass which absorbs the infra-red heatrays, such glass assuming the form of a sleeve of suitable thicknesssurrounding the luminous source, an annular space being left betweentheluminous source and the sleeve, through which a suiiiciently strongcurrent of air is passed to get rid of the heat.

Said heat absorbing glass might be applied, with the same end in View,to the construction of the silvered reflecting surfaces as at presentused, the infra-red heat rays being then arrested during their doublepassage through the glass.

In this case, the reflecting surfaces are cooled by placing them incontact with a sheet of copper provided with fins or in contact with asubstance having a great latent heat of fusion. I

In the accompanying drawings, forms of construction of the variousimprovements in accordance with the invention have been illustrateddiagrammatically and merely by way of example.

In these drawings Fig. 1 is a longitudinal sectional elevation of alightin apparatus which does not throw shadows, ofdmown type, and fittedu with an emergency lighting system in con ormance with the invention.

Fig. 1 shows the feeding circuits of the principaland emergency lightingapparatus respectively. I

Fig. 2 shows a form of construction of the device for absorbing theheat.v

gig. 3 shows an alternative form of Fig. 2 an Fig. 4 anotheralternative.

The shadowless lighting device illustrated in Fig. 1, essentiallycomprises, in the known manner, a central luminous source 1 about whichan optical system is arranged, for example a Fresnel annular lens 2which throws the luminous rays emitted by the source 1 on to a reflector3 either conical or having a plurality of'facets, in a horizontal orpractically horizontal sheet. In its turn, the reflector 3 reflects theluminous rays, c0ncentrating them at the same time, on to acomparatively small surface of the operating bench 4. This surface isconsequently lit up without shadows.

This is a known type of shadowless lighting device, but it should benoted that the .improvements which will be described hereinafter are notsolely adaptable to this type of device, but are on the contraryadaptable to all devices of the same type whatever may be the particularconstruction either of their central luminous source or of theintermediate optical device and the outer reflecting system.

According to the invention, the illuminating apparatus is fitted up withan emergency lighting system preferably constituted by a plurality ofluminous sources such as 5 whose circuit is so formed that said electriclamps 5 shall be completely independent of the principal source 1. Tothis end, their circuit may be shunted across the circuit of thesource 1. It will be more advantageous to render the circuit of thelamps 5 completely separate from that of the lamp 1 and it may be fed,for example, through a'battery of accumulators. Under these conditions,whatever may be the cause of the stoppage of the source 1, the auxiliarylamps 5 will give the requisite emergency illumination. This arrangementob viates the drawback obtaining with the devices known hitherto withwhich operations were sometimes interrupted on account of a breakdown inthe lighting of the principal source 1. With the above mentioned device,when the source 1 fails, the lamps 5 will give sufficient light toenable the surgeons to continue operating." The lamps 5 will moreover beso located that they provide by themselves light to a certain extentwithout shadows.

Again, it should benoted that said lamps 5, when they are used, inconjunction with the luminous source 1, light up to advantage theportions fringing the operating bench which a-re'normally not lit up bythe principal luminous source 1.

In certain 'cases, it may be of advantage toimprovement with which theinvention is'concerned which enables the heat given off by the principalluminous source or sources 1 to be absorbed, has been illustrated inFigs. 2 to 4.

The heat given off by the luminous source 1 may likewise be absorbed bymeans of glass composed of silica, sodium oxide, calcium oxide,arsenious oxide and iron oxide and which absorbs the infra-red heat raysemitted by the source 1.

In the case illustrated in Fig. 2, a cylindrical sleeve 8 made of glassof this composition is inserted between the Fresnel annular lens 2 andthe source 1. The luminous rays emitted by the source 1 are obliged topass through said sleeve which cuts off the heat rays. In order toprevent the sleeve 8 frbm heating up, a fairly strong current of air ispassed through the space provided between the sleeve 8 and-the luminoussource 1 whereby the heat absorbed is conducted away.

In order to absorb the heat, the device illus- 1 cooling fins or withany other substance possessing a great latent heat of fusion.

Finally, as illustrated in Fig. 4, the abovementioned glass of specialcomposition may take the form of a disc 9 closing the lower part of thecupola formed by the reflector 3. In this instance likewise, theluminous rays are obliged to pass through the glass and the heat raysare consequently arrested. Moreover, the glass might be arrangedin anyother manner, it being essential that the rays emitted by the luminoussource 1 be obliged to pass through it.

It will be readily realized that with any one of these devices, theluminous rays which are concentrated on the operating bench do not carry.heat with them and that they are consequently not liable toinconvenience the surgeons even after a considerable length of time.

As has been already said, it is evident that the improvements describedabove as applied to a special type of shadowless lighting device, areapplicable without being modified or only with unimportant modificationsof detail, to all shadowless lighting devices whatever their particularconstruction may It is moreover self evident that the-in ent'ion hasonly been described and illustrated here in a purely explanatory but bynomeans I limitative' manner, and hat itcould be'subjected to variousmodificati ns of detail with- 4 out departing from the spirit thereof.

I claim:

1. In a lighting device, the combination with a principal light source,an optical condensing means adapted to condense light rays emitted bysaid source, and a system of reflecting mirrors adapted to reflect saidrays on to a surface so situated relative to said principal lightingsource as to receive shadowless illumination, of emergency light sourcescompletely independent of said principal source and so disposed withrespect to said reflecting mirrors as to contribute substantiallyshadowless illumination to said surface. 2. In a lighting device,thecombination with a principal electrical light source, an opticalcondensing means adapted to condense light rays emitted by said source,and a system of reflecting mirrors adapted to reflect said rays on toasurface so situatedrelative to said principal lighting source as .toreceive shadowless illumination, of emergency electrical light sourcescompletely independent of said principal source and so disposed withrespect to said reflecting mirrors as to contribute substantiallyshadowless illumination to said surface, and independent electricfeeding circuits for said principal and auxiliary sources respectively.

3. In a lighting device, the combination of a lighting source, anannular Fresnel lens disposed about said source, a system of reflectingmirrors surrounding said Fresnel lens and adapted to reflect the lightrays on to a surface so situated relative tosaid lighting source as toreceive sha-dowless illumination, and a cylindrical sleeve insertedbetween said light source and said annular lens, said sleeve being madeof heat absorbing glass adapted to cut oif the infra-red heat raysemitted by said source.

4:. In a lighting device, the combination of a lighting source, anannular Fresnel lens disposed about said source, a reflecting systemsurrounding said Fresnel lens and so disposed as to produce shadowlessillumination on a given surface, and a cylindrical sleeve insertedbetween said source and said Fresnel lens and made of heat absorbingglass adapted to cut off the infra-red heat rays emitted by said source.

HENRI LUGLIEN MARIE JOSEPH BENARD.

